Re: Problem with Roland Chorus circuitry


"Thomas Hopf" <Thomas.Hopf@xxxxxx> wrote in message
news:1142941020.943508.271840@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Gareth Magennis wrote:

The noise could be on the power supply to the BBD's. Is it a different
supply than to the rest of the audio? You really do need a scope to see
this. (I can't display your GIF files either, you do need to fix them).

Very strange... can you access the webpage itself
(http://www.thomas-hopf.de)? If not, it might be some problem with
nameservers as I changed my webspace provider just one week ago.

Perhaps the following ones work:
http://thomas-hopf.de.dd12808.kasserver.com/downloads/manuals/vp330_mk2_3und4.gif

http://thomas-hopf.de.dd12808.kasserver.com/downloads/manuals/vp330_mk2_29und30.gif


Otherwise it could be a faulty component somewhere. Noisy resistors are
rare but I found one once.
You could buy a can of freezer spray. If you are lucky, and this doesn't
always work, spraying onto the faulty component will change the noise
characteristics of it.

Thanks for your input, we'll look at the power supply again. Just one
of the few possibilities... power supply or the clock signal isn't
correct.


The BBD's may require an unusual supply, that is my point. The audio will
want something like + and - 15 volts, the BBD's may require something like +
an - 5 volts. There may be localised zener diodes providing the supply
voltage to the BBD's. Check this out.








However, we put capacitors into the power supply of the concerned board
to smooth the current and it didn't help at all.

We checked if the resistors have the right resistance, but I guess a
noisy resistor can't be identified that way?
We changed all electrolytic capacitors, but one or two capacitors of
another type were left. They worked, but had a decreased capacity (I
think 9 or 10 uF instead of 15). Might they be responsible?

Oh well - if we had an oscilloscope...

Regards,
Thomas



.

Relevant Pages

  • Re: Problem with Roland Chorus circuitry
    ... (I can't display your GIF files either, you do need to fix them). ... we put capacitors into the power supply of the concerned board ... We checked if the resistors have the right resistance, ...
    (rec.music.makers.synth)
  • Re: OT: (very) Vinyl 78s value
    ... A lot of wartime carbon stick resistors were poor tolerance and tended ... of rumble being generated by the filter itself. ... But, erm, how does this work without totally buggering up the audio ... rejection at 45 Kc/s and 12dB per octave rejection of any other signals ...
    (uk.comp.sys.mac)
  • Re: Old capacitors in old radio
    ... they mention the Silver Mica caps (which came ... I made ceramic capacitors in the late 60's and early 70's for Sprague ... conductive ink and bake it on, solder on leads and cover coat. ... Now I am thinking how they make resistors. ...
    (sci.electronics.repair)
  • Re: Wall of RAM
    ... a couple hundred LEDs could be nice for a whacky project. ... but what about actually making real ram? ... > of 4,096 capacitors and PCBs. ... You'll need at least 8,192 transistors and 16,384 resistors, to make yea ...
    (sci.electronics.basics)
  • Re: TDS 1002 to read high voltage
    ... "anirudh = DANGEROUS BLOODY IDIOT" ... ** Nonsense - resistors have max voltage ratings. ... got to be very short duration indeed. ... Capacitors DO have parasitic resistances.And they DO take time to ...
    (sci.electronics.basics)